Development of a compressor icing test rig and practice of teaching reform

Marine gas turbines are highly susceptible to the formation of ice crystals under the combined influence of low-temperature environments and wave splashing in polar regions, particularly at the inlet guide vanes and the initial stages of the blades of the compressor. The phenomenon of ice accumulation at the inlet of a gas turbine results in a reduction of the surge margin of the compressor. Ice shedding can lead to blade deformation or fracture, which poses a significant threat to navigation safety. Concurrently, within the pedagogy of power engineering and engineering thermophysics, with a foundation in ship and marine engineering, fundamental knowledge points, such as the thermodynamic process of compressors, remain opaque. Moreover, there is a paucity of experimental instructional materials for measuring compressor blade icing, which are aligned with engineering practice. Consequently, the development of a compressor icing experimental teaching platform, the conduction of experiments on the icing characteristics of three-dimensional compressor blades, and the undertaking of teaching reform research are of paramount importance for ensuring the safe operation of marine gas turbines on polar ships and the enhancement of talent training quality

The present study proposes the development of an annular icing wind tunnel experimental teaching and research platform to be integrated with natural low-temperature environments. A three-dimensional stationary blade of a marine compressor was selected as the object of study, and real icing working conditions were simulated by controlling parameters such as airflow velocity, droplet diameter, and liquid water content. The ice knife method, the grid method, and the laser particle size analyzer are used to measure key parameters, and a three-dimensional blue-light scanner is employed to extract ice shape data. In conjunction with the uniced blade data, a quantitative analysis of the icing characteristics is conducted by establishing the icing area ratio and ice thickness parameters. This analysis is complemented by the design of multi-parameter coupled experimental teaching cases.

Icing is primarily concentrated at the leading and trailing edges and on the pressure surface of the blade. This results in an uneven distribution along the blade’s height, with a strong central area and weaker blade roots and tips. Rime ice forms easily at low temperatures (below −9.5 ℃), while clear ice forms at relatively high temperatures (between −3.0 ℃ and −5.5 ℃). The maximum ice thickness occurs at the stagnation point of the leading edge and increases significantly with rising liquid water content. Through the experimental platform, students can simulate low-temperature environments, capture ice shapes, and conduct quantitative analyses of icing laws and compressor performance degradation. This allows them to gain a deeper understanding of the thermodynamic processes of compressors.

The novel, natural, low-temperature icing wind tunnel experimental platform effectively simulates the icing conditions of marine compressor blades in polar environments. This provides a reliable basis for researching the icing mechanism and developing anti-icing and deicing technologies. By conducting compressor blade icing measurement experiments, the effects of airflow velocity, droplet diameter, and liquid water content on the icing processes of three-dimensional compressor blades have been clarified. This work consolidates students’ theoretical foundation in thermodynamics and cultivates their scientific innovation capability. It is crucial for researching the icing and anti-icing of gas turbines on polar-navigated ships, as well as reforming the experimental teaching methods for compressor thermodynamics processes in Engineering Thermodynamics courses.